对象类型和装箱

Question

MSDN says that

The object data type is the type to and from which objects are boxed.

I thought only value types are boxed? Now I am bit confused. So when I assign reference type variable to object variable, its boxing?

Answer 1

It just states that System.Object is the type used when any object is boxed.

In other words, when a value type is boxed, it is boxed within System.Object type.

Answer 2

Only value types are boxed.

So, to be accurate the sentence should be:

"The object data type is the type to and from which values are boxed."

Answer 3

Yes only value types are boxed. Boxing a value type packages it inside an instance of the Object reference type. What this statement says is that it is System.Object which is used to box/unbox value types to and from.

Answer 4

Boxing is only done on value types. I'm wondering though why MSDN doesn't state it more precisely.